A.T. Robertson Commentary Colossians 3:23

"whatsoever ye do, work heartily, as unto the Lord, and not unto men;" — Colossians 3:23 (ASV)

Whatsoever ye do (ο εαν ποιητε). See same idiom in 3:17 except ο instead of παν οτ.

Heartily (εκ ψυχης). From the soul and not with mere eye service. In Eph 6:7 Paul adds μετ' ευνοιας (with good will) in explanation of εκ ψυχης.

As unto the Lord (ως τω Κυριω). Even when unto men. This is the highest test of worthwhile service. If it were only always true!